+.IP \fBtun_flags=\fIflags\fR
+Matches flags indicating various aspects of the tunnel encapsulation. Currently,
+there is only one flag defined:
+.IP
+\fBoam\fR: The tunnel protocol indicated that this is an OAM control packet.
+.IP
+Flags can be prefixed by \fB+\fR or \fB-\fR to indicate that the flag should
+be matched as either present or not present, respectively. In addition, flags
+can be specified without a prefix and separated by \fB|\fR to indicate an exact
+match.
+.IP
+Note that it is possible for newer version of Open vSwitch to introduce
+additional flags with varying meaning. It is therefore not recommended to use
+an exact match on this field since the behavior of these new flags is unknown
+and should be ignored.
+.IP
+For non-tunneled packets, the value is 0.
+.IP
+This field was introduced in Open vSwitch 2.5.
+.